[140274] in North American Network Operators' Group
Re: How do you put a TV station on the Mbone?
daemon@ATHENA.MIT.EDU (Michael Dillon)
Sun May 8 02:10:58 2011
In-Reply-To: <AF1A5103-1060-4BBE-B180-F3079A57714B@jsyoung.net>
Date: Sat, 7 May 2011 23:10:15 -0700
From: Michael Dillon <wavetossed@googlemail.com>
To: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> Many years ago I was the MCI side of the Real Broadcast Network. =A0Real =
Networks arranged to broadcast a
> Rolling Stones concert. =A0We had the ability to multicast on the Mbone a=
nd unicast from Real Networks caches.
> We figured that we'd get a hit rate of 70% multicast (those who wanted to=
see the event as it happened) and
> 30% unicast (those who would wait and watch it later).
You do realize that unicast from Real Networks caches *IS* multicast,
just not IP Multicast. Akamai runs a very large and successful multicast
network which shows that there is great demand for multicast services,
just not the low level kind provided by IP Multicast.
In fact, the most important use for IP Multicast is to work around the
problem of the "best route". In the financial industry, they don't want
their traffic to take the best route, because that creates a chain
of single points of failure. So instead, they build two multicast trees,
send a copy of each packet into each tree, and arrange that the
paths which the trees use are entirely separate. That means
separacy of circuits and routers and switches.
-- Michael Dillon
